An exciter machine produces the electrical power which is required to supply power to the field windings of a generator.
Depending on the generator rating, different techniques have been adopted for the exciter system. One generally used exciter technique comprises a directly coupled exciter machine with an auxiliary exciter machine.
Exciter machines having an auxiliary exciter machine and a separate fan are available for four-pole and two-pole generators. Both the auxiliary exciter machine and the fan are manufactured separately and each require a shrink fit on the common shaft. This lengthens the shaft and the overall machine structure, and leads to increased manufacturing and assembly effort. The previously available fans, which are composed of an aluminum casting, are also very expensive and complex.